I had this same problem on an old laptop. No sound from DVDs playing in Media Player. Also when playing in PowerDVD, the video and audio were very choppy or stuttering. Tried the AC3filter codecs, and all the tweaking of various audio and video settings, no luck. Tried the DMA versus PIO configs as well, no luck.

Solution: Uninstalled PowerDVD by cyberlink and installed WinDVD 4.0, and now my DVD's play great through WinDVD and also Windows Media Player. Hope this helps to keep someone from pulling their hair out like I was doing.